Convenience outlet with improved wire and plug blade gripping means



Feb. 10, 1959 v. R. DESPARD 2,873,433

CONVENIENCE OUTLET H IMPROVED WIRE AND PLUG BLADE PPING MEANS 2 Sheets-Sheet 1 Filed Sept. 26. 1957 INVENTOR warm R ass/ 400 ATTORNEYS Feb. 10, 1959 CONVENIENCE OUTLE Filed Sept. 26, 1957 v. R. DESPARD 2,873,433

T WITH IMPROVED WIRE AND PLUG BLADE GRIPPING MEANS 2 Sheets-Sheet 2 INVENTOR VICTOR 17. 05334190 DQMQ ATTORNEYS United States CONVENIENCE OUTLET WITH IMPROVED WIRE AND PLUGBLADE GRIPPING MEANS Victor-R, Despard, Syracuse, N. Y.,. assignor to Pass & Seymour, Inc., Syracuse, N. Y., a corporation of New. York Application September 26, 1957,Serial No. 686,459

14 Claims. (Cl. 339-95) Thisninvention relates to electric wiring devicesand more .particularlyto connecting apparatus for .circuit continuation.

It is. a general object. of the present inventionto provide novel'and improved wiring devices having unique circuit: continuing and connecting means associated therewith.

More particularly it isan object of the present inven tionzto provide a novel and improved duplexsconvenience outlethaving wire gripping terminals eachacting auto-- matically on insertion. ofv the bared conductor-pend through. an aperture in the wall of the outlet .to grip thesame in an effective electrical. and mechanical. connection.

.An important object of the present invention resides in thearrangement of doub1e...spring tongue .wiregripping devicestogether with. stationary tonguewstops whereby the-wire is savedlfrom. being cut .olf by thetongues. on:

theapplication. ofexcessive pull thereto.

Another. important object of this invention resides in thecooperating arrangement and mounting of the wire gripping elements wherebythey are. reinforced by the material ofthe housing andrestrained against movement occassioned by the thrusting of wire .ends therein.

Still another important featureof the invention resides in the arrangement of the wire grippingdevices in adual convenience outlet in such a manner that the wires leading thereto enter through/the back of the outlet housing. A'further important feature of the inventionresides in the unitary construction .of.wire grippingmeans and 'two plug bladegripping contacts. whereby the unit. ma be mounted in achannel of uniform widthwhose side walls restrainboth therwire gripping-means and the. blade gripe.

ping contacts. to result in the proper performance .of their functions.

A still-further important feature of .the. invention resides in the construction of .the plug blade grippingcontacts. whereb'ythey are flexed in torsion to exert two line con.-.

tacts .on eachblade to improve the conductivity.

An. additionalfeature of ithe invention. consists in so.

forming the plug blade gripping contacts that they present widened areas ofcontact engagement to the plug blade toreduce the frictional drag on the blade during insertion Other and further objects and features of the invention: willbe more apparent to those skilled in the. art upon.

aconsideration of'the attached specification. and'accompanying drawing wherein is disclosed a single exemplary embodiment of the invention with the understanding that such changes, additions, modifications andeIiminations.

maybemade without departing from the spiritof -the.in-. vention as expressed in' the appended claims.

In saiddrawinga.

Fig. .1 is .a front elevation of a duplex convenience. outlet constructed. in accordance with the present inven-. tionand shown full size;

Fig. 2 is a side elevation thereof; V

Fig, 3 is a plan view of the lower half of the housing showing the unitary wire gripping and plug blade holding contactsin position therein and illustrated onv an.en.-, larged scale;

Fig. 4 is a transverse section taken on broken line 4-4 of Fig. 3 showing on. the right. the wire entranceand-z gripping means. and on. the left the entranceforwire. release means;

Fig. 5 is a view similar .to. the right sideof Fig. .4 on a stilllarger scale and showing a wire held by. the gripping means;

Fig. 6 is a transverse sectional. view taken on 1ine..6+6 of Fig. 2 and showing the cooperation of the plug. blade: gripping contact parts with the restraining parts of the. housing and cover;

Fig. 7 is a much enlarged view of a portion of the left. side of. Fig. 6 showing a plug bladein positionand en? gaged by the contact therefor;

Fig. 8 is a perspective viewof one'embodiment of a wire gripping device shown removed from the outlethouse ing and incorporating integral. plug. blade grippingcontacts, one set on each. end thereof;

Fig. 9 is a horizontal section. through one of the. plug. blade gripping contact sets taken on line. 9-9 of Fig. 8;,

Fig. .lOis a view similar. to Fig. 8 but .showinganirrb proved blade gripping arrangement;..

Fig. .11 is a horizontalsection.online 111-11 lof Fig 10;

Fig. 12=is afr'agmentary side elevation ..showing.one. blade gripping'end ofa contact assembly showing further. improvements;

Fig. 13 is a plan view thereof;

Fig. 14 is a plan view of one end of a.further.embodiment of a blade engagingcontact; and

Fig. 15 "is asectional view thereof taken online 15-.-15. of Fig. 14 looking in the direction of the arrows.

In the wiring ofhomes, ofiice buildings,.factories, and. the like, many Wiringdevices. providing outlets and con-. trols of various forms must be connected to the conductor system. Especially in. flush. wiringoithe type used in. homes and offices the equipment is beneaththesurface.

of the Wall and. covered by a suitable wall. platewhile.

housed in, a switch orfloutlet box.. Theinstallation of the.- wiring presents many problems. augmented .by the connecq tionsbetween. the conductors and theterminals on..the various types of wiring dCYlCESrWhlCh have heretofore; been .of.the screw type. requiring the..wireman.to form at small loop onthe endof each wire,.fitit around the. shank. of a screw andlturndownthe screw head onto the. loop to make the connection. The time requiredbeyond. that. necessary for stripping the insulation from. the end of. each conductor is. considerable and inlarge or multiple installations the co-stof such timerunsup into relatively large figures. It. has long been the desire of the-trade to. reduce the time required forwiring .the various outlet devices and to promote this the. present inventionpro Vides a simple means forattaching. the conductors shy" merely pushing the. baredends. thereof into. openings-in. one of the;wal'ls ofthe wiring device. There .ihEvWllfi is. held by spring gripping. means instantly'providing,botht for mechanical and. electrical.v connection. between the conductor and the electrical parts of the apparatus-to; whichit is to be connected, A fewvsuchtdevices have heretofore been proposedsbut have not inugeneral beensatisfactory forregularusenand ittis thepurposemoftthca present inventionto so improve thesezearlierformssofii devices that all of theinfaultsare .overcometandsthey can? be used with high efiiciency in the rapid wiring of elec,

trical equipment of many types providing just as efficient and eifective connection as the more mechanical types requiring the use of tools and the expenditure of considerable time.

Refer now to the drawings for a better understanding of the invention which has been displayed in connection with the more or less conventional type of duplex convenience outlet such as shown in Figs. 1 and 2. This is formed of a two part molded insulation housing including base 12 and cover 13 secured together in any convenient and conventional manner as for instance by the screws 14 passing up through lugs on the ends of the base and engaging in the cover. As is customary the usual mounting strap 15 islinterposed between the two housing parts and presents the mounting and plaster cars 16 at each end for attaching the same to the usual wall box.

While the wire gripping mechanism now about to be described has been shown in combination with a duplex convenience outlet or. wall receptacle it nevertheless is adaptable for use with any type of wiring apparatus of the character used. in home, otfice, and apartment wiring where the loads are not too heavy and the illustration with a particular type of apparatus is considered as rep resentative only. It should be remembered that because of the character of a duplex convenience outlet the shape and arrangement of the wire gripping parts may be slightly difierent from those required in other apparatus such for instance as switches, lamp sockets, and the like.

It will be seen from Figs. 3 and 6 that the hollow base 12 of the housing is divided into two elongated parallel compartments arranged side by side across the width 4 extension by means of the side walls of these compartments or the ramp structures previously referred to. To resist the upward thrust of wires being inserted in the slots 28 in the wire gripping devices as well as to hold these structures in position in the bottoms of their respective compartments a single transverse thrust plate of insulating material may be provided as seen at 35 in Figs. 3, 4, and 5. The edges of this sheet of insulating material fit in slots 36 in the side walls of the housing and its upper edge is shaped to be engaged by the housing cover to hold it in position with its lower tip portion at the center resting in the notch 23 in the bottomof flie housing wall as previously mentioned. Over the transverse centers of the respective wire gripping devices the plate is cut awayas seen at 37, but at the points 38 adjacent the outer edges of each of the wings 30 there is contact along a narow line with the strip 25 so that when wires are thrust in through the bottom of the housing they cannot liftthe wire gripping devices in their compartments.

thereof. These compartments 17 have parallel side walls,

the outer wall 18 of each being defined by the side of the housing. The inner walls 19 are defined by vthe partition 20 extending longitudinally through the center of the housing and being of varying heights at different portions of its length as clearly seen in the figures. In its center it is slotted down to the level of the bottom wall 22 of the housing which is recessed at 23 for a purpose later to be described.

Fitted closely into each compartment 17 and having areas resting on the bottom wall thereof is one of the combination wire and contact gripping units 25 best seen in Figs. 8 and 9 formed from a single relatively thin sheet of Phosphor bronze or similar good conducting and yet springy metal. spaced apart a distance equivalent to that between the side walls of the compartment 17 whereby these side walls resist any lateral thrust resulting from the use of the part 25 in carrying out its regular functions. To assist in this and to insure a tight fit against these side walls theymay be slightly tapered both for convenience in molding and to provide snugness, but a simpler way to facilitate it is by the use of slightly inclined ramps such as shown at 27 in 4. The intermediate portion of the part25 forms the wire gripping section and for this purpose it is longitudinally split as seen at 28 between two punched openings 29 near the ends of the bottom. The two opposing wings 30 thus formed are bent upwardly out of the plane of the metal so a to provide upward inclinations from the lower surface forming a funnel-like entrance for the circuit wires which are introduced into the slot 28 through appropriate holes in the bottom wall of the housing as seen for instance at 31 in Figs. 3, 4, and 5. For each of the wire gripping strips as shown in Fig. 8 two openings are preferably provided,

one for the wire normally conducting current to the unit and the second for any extension of the circuit found desirable.

-As before mentioned, the contact and wire gripping strips 25 fit'snugly into the compartments provided for them in the lower portion of the housing and the end sections 33 rest against the bottoms of the compartments with the edges 26 of the strips supported against lateral This sheet has parallel edges 26 Having recourse to Fig. 5 it will be seen how the stripped end 40 of a wire is introduced through the opening 31 in the bottom wall of the housing, pushes the wings 30 apart, and passes between them. They are tightly held against the wire by reason of their inherent resilience and grip it at such an angle that any tendency to withdraw the wire causes further gripping thereof insuring both a tight mechanical and an effective elec trical engagement. To prevent excess pull on the wire causing the edges of the wings 30 to approach suificiently to completely cut off the wire, limiting abutments are provided surrounding each wire entrance hole and having inclined sides 41 adapted, when the wings '30 are unfiexed, to loosely engage their under surfaces as seen at the right in Fig. 4. When a wire of suitable size is inserted through the slot 28, the wings are lifted from these surfaces 41 so as to become effective in holding the wire as seen in Fig. 5. Any excessive pull on the wire, however, will draw the wings down against the barrier surfaces 41 which prevent their edges from coming closer together than of an inch so that the wire cannot be cut off. At this point it might be well to note that the holes 31 and the slot 28 in the wire grips are sized to receive the standard No. 12 and 14 wires used, in most all household wiring. The wires are respectively 81 and 64 mils in diameter. No selection is necessary, either size being received in each of the holes provided for the purpose.

In the event that for any reason a wire that has been I inserted must be removed it is not necessary to separate the two parts of the receptacle for the purpose. Rather asingle central opening 43 is provided in the housing floor for each of the wire gripping units. This is sized to receive a conventional S-penny nail which is readily available on all construction jobs. When one is thrust in its tapered point passes into the slot 28 and springs' the wings 30 suificiently far apart to release the wire which may then be readily withdrawn it it does not fall out. The deep notches 44 in the hold downplate'SS, are provided to limit the insertion of the end of this, nail which enters at the center directly-in line therewith. Thus only the tapered point enters between the wings 30' and the nail can easily be withdrawn since the wing edges cannot get a grip on it because of the slight included angle between them and the point sides. 1

By arranging the dual outlet as shown the two wire. gripping devices are made of adequate length so thateach may receive two wires and also provide space for. the. releasing nail. At the same time the arrangement is such that both wire gripping devices are in the bottom. of one single piece of the housing for the whole unit andthus their side. walls are rigidly restrained by a. non-resilient one piece construction. This insures against, anyspreading of the sidewalls of the spring wings 30. when tension is applied to a wire which has been in; serted between them; Thus no unwarranted releasejis mars-gass ever "etfectedi For the sake: of lightness the barrier wallf 2(l'b'etween the two compartments 17is cut down as low as possible consistent with safety between the two wire gripping devices of different potential but at the endsas shown at50 it is of full height for a reason now about to be explained;

The arrangement and material of the wire gripping strips 26 make it extremely convenient to apply to them; any of the improved forms of attach'mentpltig blade gripping contact shownin the drawings and forming a portion of the present invention. These contacts are integral, one With each end of each wire gripping strip and are constituted by turned up portions at the-ends-thereof. These turned up portions each comprise two spaced co planar furcations 52 of complementary form: Where they leave the flat bottom portion of the strip 26'they are relatively wide but taper to formthe cutout 53 of increasing width. Thetop of theopening is defined-by the widened portions consisting of wings54 extending; generally toward each other from the furcations. The, upper portionsof the wings extendabove the furcations, which stop midway of the "length of the wings as at 55;, The facingedges of the wings are separated by a narrow parallel walled slot 56 and like the wings 30 are bent, both in the same direction, away fromthe; plane of the material of the strip where it is turned up at the end.

As seen in plan in Fig. 3, the narrow space 56 between the wings is slightly less than the thicknessof a plug blade such as shown at 58 in Fig, 7 engaged between the Wings 54 whereby the edges of the latter engagethe sides of the plug blade in line contacts thus giving an extensive contact area not usually available in the conventional form of plug blade engagement which has only point contact.

As also seen in Fig. 3 as well as in Fig. 6, the outer edges of'the furcations 52 closely abut against the side walls of theflower portion .of the housing as well as against the high portions t? of the separating partition between the compartments. 17 and thus the wings are constrained against lateral displacement by the insertion v of a plug blade.

It will be remembered that the upper ends. of the furcations 52 are cut oil sharply at 55 and this is to provide surfaces for engagement by the lugs 68 depending from thecover. These lugs rest on surfaces 55 to insure the restraining of the ends of the contact strips 26 in their compartments even though plug blades are being withdrawn. The action of these lugs 60 may be all that is necessary'to restrain the. whole gripping strip so that the septum 35, may be eliminated. These. lugs 6il-of which there are four acrosseach end of. the receptacle, as seen in Fig. 6, also engage the. edges of wings 54 where-they extend above surfaces SSand insure against this portion of them spreading." The upper-corners of. the wings. areclipped. orchamferedas at 62to facilitate the insertion of a plug blade, the position of which is determined and guided by appropriate slots,.63 in :the cover plate in the normal manner.

When the plugblades are inserted thewings are .pre vented from spreading laterally and. are prevented from moving toward the ends of the compartments .bythe column-like struts 64 best seen in Fig. 3; The space necessary to receive the plug blade, which is thicker than the width of slot 56 between the Wings is effected by inserting the blade between the chamfered corners which twists the wings oppositely in a manner to place a torsional stress on the furcations 52 inthe areas between the wings and the bottoms or flat portions of the strips26. This puretorsional stress insures that the wings will give the edgewise line contactdesireds It furthermoreprovides a great deail more force than can be achieved by any other manner of stressing-the spring within the areas available and provides therefore one of the most eifectivecontacting arrangements known both 6' for insuring good electrical contact *andproviding tight mechanical'holding so that the plugdoes not pull out when reasonable tension isappliedto the cord attached thereto.- It willbe obvious that the type of plug blade' gripping mechanism just "defined is not restricted to use; withthe specific wire gripping mechanism defined earlier in this specification but the unit ill'ustratedin Figs: 8 and '9 does combine these two devicesinto a single onepiece structure which makes use ofthe resilience ofa' single flat strip of sheet metal to provide bothwiregripping and plug blade gripping in the-manner already defined.

Under some circumstances and with certain typesof plugblades, such as those recently becoming popular and formed by folding a thin sheet of metal to double its thickness, the pressureyexerted 'on the blade by the raw cutedges'of the wings 5 5 of the embodiment shown in Figs. 8 and 9, produces more than the desired amount of frictional engagement, making the insertion of the plug blade or its withdrawal xtoo difficulein" many instances.

To" eliminate this fault. without disturbingthe principal advantages of the plugblade gripping contact arrange ments shown in Figs. 8 and 9, a modification as illustrated, in Figs. 10 and 11 may be resorted to. Here the principal difference is best illustrated in the section view, Fig. 11, where the sharp corners or edges bearing the reference character 65in Fig. 9, and which are somewhat rough as a result of the cutting operation for separating; the wingsyare'bent over to form small flanges or ribs 66 which present relatively flat, smooth faces 67" to the. sides of "the gripped plug blade. This lifts the. raw cut edges from engagement with the blade faces andialso increases the area of contact, whereby the unit contactpressure is' reduced and theamount of. friction substantially die creased so that less effort is requiredto insert the plug or to remove it, although sufficient friction remains to insure it being retained in the receptacle against any normal withdrawal strains.

In the embodimentillustrated inFigs. 12 and 13; which is cumulative with that of Figs. 10 and 11, the smoothness of insertion of thetip of the blade is improved by forming the V-notch, such as isdesignated 70 in Fig. 8,.

by folding over the upper corners of the wings afterfirst clipping them slightly as at 71 in Fig. 13. The folded over portion is designated 72 and actually extends substantially at right angles to the plane of'the wing 73 Wl'liChilSClfhfiS substantially the same angle to the main. portion 52 as seen in Fig. 8. This then eliminates any" raw .cut edges over whichthe tip of the plug blade must slide during insertion. Moreover, the flanges 72 on the. wings are in effect somewhat transverse thereof. and provide additional rigidity-against bending, insuring that the actionpwhich accounts for the excellent contact engagement of the wings with the faces 'ofthe'plug blade comes from twisting of the reduced section portions. such as designated74 in Fig. 10;

It willbe remembered that the contact blades. of many attachment plugs are transversely drilled closely adjacent their tips, as indicated at 75 in Fig. 7, in order to cooperate witha slight projection on some of the flat type contacts which are so lacking in friction as to need this ongagement to insure holding the plug in position against accidental withdrawal. This rather large diameter straight through hole is very close to the tip and inco-nstructions suchas illustrated in Fig. 7, as well as in Figs. 8 and 9, the sharp lower corners 76 of the wings 54 may spring sufficiently into such a hole as to make the withdrawal of the plug exceedingly difficult, if not impossible under certain circumstances, and to obviate this difficulty theselower corners in the embodiment of Figs. 12 and13 area diagonally bent inwardly and upwardly as seen at 77 in Fig. 12; to provide a smooth incline, over which theedges of the. hole. 75 inthe blade can slip without difliculty so:

that. no resistancev beyond that. exertedrby the frictional contact on the blade resists its withdrawal.

In yet another formof blade engaging arrangement, asseen in Figs. 14 and 15, each of the wings 54 is maintained in the same plane as its corresponding furcation 52 to present one long continuous transverse plane as seen at 80 in Fig. 14, and this may be edged by flanges 81 whose inner faces are substantially parallel to each other where they are intended to engage the faces of the plug blade. To achieve the condition illustrated in Fig. 14 the portions of the furcations below the lower ends of the wings are twisted in the areas designated 81'which areas also take the torsional twist when the plug 'blade is inserted. As in the other embodiments the top edges 82 of the wings may be either chamfered or turned over as in Fig. 12 and a similar treatment given to the lower corners as illustrated at 83.

The plug blade receiving contacts of all of the embodiments can be readily incorporated in single outlets as will be obvious, the type of wire terminal being inconsequential.

This application is a continuation-in-part of my application Serial No. 378,380 filed September 3, 1953 now abandoned and entitled Convenience Outlet With Improved Wire and Plug Blade Gripping Means.

Having thus described my invention, what I claim as novel and desire to secure by Letters Patent of the United States is:

1. A duplex convenience outlet having in combination, an insulating housing formed of a plug blade guiding cover and a body part providing two longitudinal, side-by-side compartments having bottom walls common with that of the body, a strip of resilient conductive metal mounted against the bottom of each compartment and having the ends thereof turned up normal to the bottom, each such end being longitudinally split providing wings deflected in the same direction through a small angle out of the plane of their end to receive tightly between them a plug blade entering through said cover whereby the wings are stressed in torsion, each said strip between the said ends having a pair of wings deflected up from the bottom wall to guide the bared end of a conductor wire between their edges and to there hold the wire against withdrawal, said bottom wall having a wire guiding opening therein for and in alignment with the space between said last mentioned wing edges.

2. Electric wiring apparatus as defined in claim 1 wherein the side walls of said compartments engage the outer edges of the upturned ends of said strips to prevent spreading thereof.

3. A receptacle for an attachment plug having a generally flat blade comprising in combination, a housing having a compartment, a cover for said compartment having a blade entrance opening, a contact in said compartment formed integrally of a resilient sheet metal strip and having a base, upturned, spaced furcations and an elongated wing on the inner edge of each furcation and extending above the latter, said wings including between them an angle of less than 180 degrees, theinner edges of the wings being spaced to receive between them and tightly 3 contact a plug blade projecting through said entrance opening and means to attach a conductor to said contact. 4. The receptacle defined in claim 3 in which the Walls of said compartment substantially engage the outer edges of said furcations to prevent their spreading under the stress of an inserted plug blade. I

5. The receptacle as defined in claim 4 in which the said cover is provided with lugs engaging the tops of said furcations to hold the contact in position in its compartment. -6. The receptacle as defined in claim 4 in which the housing has an end wall for said compartment intersecting fulcra for the furcation edges.

7. In a duplex convenience outlet, in combination, an insulating housing having entrance slots for the two blades of each of two attachment plugs and having therein two i 70. those engaging the furcatlon edges so as to provlde corner 81 laterally spaced, longitudinally extending chambers each entered by one of said slots for each plug, a one piece, sheet metal, conducting fitting in each chamber including spaced plug blade engaging and holding furcations at each end thereof and automatic wire engaging and holding means intermediate the ends, the portions of each fitting connecting the furcations thereto being reduced in width providing narrow parts whereby each furcation performs its plug blade engaging function under the action of torsional stresses in its adjacent narrow part.

8. The outlet defined in claim 7, wherein the plug blade engaging and holding fnrcations include the adjacent parallel edges of relatively inclined wings, the outer edges of said fnrcations being parallel to and spaced from the adjacent edges, and means forming walls of said chambers substantially engaging said outer edges to resist spreading and insuring said torsional stressing.

9. Electric wiring apparatus including in combination, an insulating housing, a contact in said housing and means for connecting a conductor to said contact comprising a flat strip of resilient metal connected to the contact, resting against a rigid wall of the housing and provided with integral facing wings bordering a slit in the strip, said wings being bent outwardly from said wall to be spread r by a conductor wire introduced between them through an ing a blade entrance opening, a contact in said compartment formed integrally of a resilient sheet metal strip and having a base, and an upturned portion substantially normal to said base, a central aperture in said portion adjacent its junction with the base, a slit connecting the aper ture to the free end of the said portion and forming contiguous wings, said wings being deflected to overhang the base and separate the edges of the slit to accept a plug blade extended through said opening by engaging its oppo-' site faces longitudinally, the insertion of the blade stressing the narrowed areas beside said aperture torsionally.

. 11. The receptacle as defined in claim 10 in which the edges of said slit are formed with narrow flanges each turned in the same direction as its wing deflection.

12. The receptacle as defined in claim 10 in which the corners at the junction of the slit edges and the strip end are folded over to provide a smooth converging entrance to the space between the slit edges.

13. The receptacle as defined in claim 10 in which the corners at the junction of the slit edges and the central aperture are relieved sufliciently to avoid catching in a hole in the lower end of a plug blade.

14. Electric wiring apparatus having in combination, an insulating housing, an electrical contact in said housing and means to connect a conductor to said contact comprising a strip of resilient metal connected to the contact and having a slit therein, the metal of the strip adjacent said slit being formed into converging wings to guide and receive a bared conductor between the facing free edges of said slit to grip the same and resist withdrawal, said strip being elevated and shaped to be engaged by said wings. when deflected on excess conductor withdrawal effort to hold the slit edges apart sufficiently so that conductor cutoff is prevented.

(References on following page) References Cited in the file of this patent UNITED STATES PATENTS Schellenger July 31, 1928 Smart Mar. 13, 1934 Del Camp Oct. 21, 1941 Shenton Nov. 10, 1941 Deal Camp Aug. 15, 19 50 Sanda Nov. 11, 1952 Hubbell Mar. 2, 1954 FOREIGN PATENTS Germany Sept. 15, 1917 Great Britain Oct. 24, 1951 

